1. Field of the Invention
The present invention relates to ambient air sampling impactors that are simple and compact, and capable of being worn by a person for air sampling.
2. Description of the Prior Art
Inertial impactors used for sampling air to determine the quality of the air are well known. Impactors classify airborne particles by their aerodynamic diameter, which is the same particle property important in predicting the disposition of the particle in human airways.
The most standard design for an impactor is to have a jet of particle-laden air impinging upon an impaction plate, so that particles with high enough inertia will impact upon the plate and be separated from the air stream, and those which are small may be carried through one or more additional stages in a cascade impactor, or may be immediately passed through a filter where they are collected. If several impactor stages are used, and the particles collected at each stage are analyzed, information on the size distribution of the particles in the air is obtained. It is also a fairly common to have just a single stage impactor where the particles larger than a cutoff size are separated out, and the smaller particles are collected on a filter.
Personal air samplers are worn on the body of an individual. An air pump is also carried by the individual, for example, on a belt. These samplers are sometimes cyclones, such as the prior art Dore-Oliver Cyclone, and in some instances impactors have been used for personal sampling as well. Normally a single stage impactor followed by a filter is the most convenient because it is much lighter than a conventional cascade impactor and, of course, since the instrument is to be worn by an individual, both the weight and compactness of the instrument have to be considered.